Many types of dairy equipment or other equipment are required to be cleaned-in-place and this cleaning must be made frequently in order to comply with the sanitation laws of the various states. Various materials must be used in the cleaning solution to insure absolute cleaning of the interior of the pipes, etc., for example, an acid must be used to cut the residue milk from the pipes in milking systems. A detergent is also used to thoroughly clean the equipment and when the cleaning cycle is finished, the system must be flushed with clear water and then preferably sanitized. As a result, various sequences of cleaning operations must be performed in timed relationship in such equipment. One example of milk line equipment with which the present invention finds utility is shown in the U.S. Pat. No. 3,191,576 issued June 29, 1965 to L. F. Bender and entitled "Milk Line Releaser and Washing Apparatus". That apparatus utilizes automatically operated releaser apparatus of the vacuum type and in which the cleaning solution is held in a large tank and circulated through the milk line and vacuum releaser apparatus to thoroughly clean the same.
Another example of equipment with which the present invention finds utility is shown in U.S. Pat. No. 3,802,447, issued Apr. 19, 1974 to L. F. Bender and entitled "Automatic Tank Washer with Spin-Burst Mechanism for Washing, Rinsing, and Sanitizing." That apparatus automatically washed milk storage tanks by means of appropriate steps in a washing cycle.
Another example of apparatus with which the present invention finds particularly utility is shown in U.S. Pat. No. 3,921,692 which issued Nov. 25, 1975 to Rolyn A. Schmid and which has been assigned to an assignee common with the present invention. The pump in that patent performed satisfactorily, but is subject to difficulties in manufacturing and operation due to the concentricity problems required in its construction. Furthermore, that pump was costly to manufacture.
Pumps of the character to which the present invention pertains are used in equipment such as cleaning-in-place apparatus and must be simple, effective, and easy to clean. Pumps of this character must also be kept sterile and in order to facilitate such cleaning, it is necessary that each component used in milk handling equipment be as simple as possible and easily assembled and disassembled. Furthermore, as these pumps are frequently used to pump different fluids, or for other purposes, they must be frequently stopped and started and heretofore it has been a problem to prime such pumps each time it is desired to again start them.
Furthermore, these pumps must be stable in use, economical to manufacture, reliable in operation and adjustable and primed in a quick and easy manner.